(1) Field of the Invention
The present invention relates to fluorine-containing compounds having hetero cyclic triazoles, tetrazoles, thiazoles, and thiadiazoles of amide as substituents.
The lubricants in accordance with this invention may take the form of solid and liquid or fluid lubricants and can be used for the lubrication and rust-prevention of the contact surfaces of a machine or equipment with moving parts, in which applications they will produce a superior effect.
(2) Description of the Prior Art
Fluorine-containing lubricants as part of the synthetic lubricants are known to include fluorosilicone oil, polyfluorochloroethylene oil, and perfluoroalkyl polyether.
While these compounds are used for their heat resistance and chemical inertness as the main properties favoring their application for this purpose, they present many deficiencies in their lubricating behavior due to their inherent adsoptivity.
In an attempt to overcome this shortcoming, U.S. Pat. No. 3723317 (Mar. 27, 1973) purports to improve these properties by the addition of 1,3,5-triazine to the fluorine-containing lubricant base oil. Recently, it is described in the Japanese Patent Provisional Publication No. 155345/86 of the Italian company Montedison S.p.A. and in the Japanese Patent Provisional Publication No, 93769/88 of the Swiss company Ciba Geigy, and E. J. Soloski, G. J. Moors and Christ Tamborski have published papers on the synthesis of 2- and 2,5-substituted benzoxazoles and benzothiazoles in the Journal of Fluorine Chemistry, 8 (1976), pages 295 through 304, and K. J. L. Paciorek, J. Kaufman, J. H. Nakahara, T. I. Ho, R. H. Kratzer, R. W. Rosser, and J. A. Parker on the Synthesis and Degradations of Fluorinated Heterocyclics III. Perfluoroalkyl and Perfluoroalkylether 1,3,4-Oxadiazoles in the Journal of Fluorine Chemistry, 10 (1977), pages 277 through 288, and Kalathil C. Eapen and Christ Tamborskion the Synthesis of 2-(Perfluoroalkylether)- and -(Perfluoroaryl) Benzothiazoles in the Journal of Fluorine Chemistry 12 (1978), pages 271 through 280 concerning the use of these compounds as anti-corrosive agents.
The application field in which these lubricants have been used in recent years include, for example, such electronic equipment areas as electromagnetic disk surface, connector and electric contactor lubrication, and many of these applications make use of inorganic and organic materials. It has been realized, however, that the service life of the equipment is difficult to extend simply and solely on account of the lubricant's wetting behavior.
Moreover, in bearings with oil and grease lubrication, it has been found that fluorine-containing lubricants have inadequate adhesion to metals so that, in the case of general bearing steels, their use will lead to poorer corrosion protection and a reduced bearing service life, a problem that needs to be resolved. Fluorine-containing lubricants are therefore attracting much attention and are being extensively used, chiefly in those areas in which chemical and heat resistance are an important requirement.
These lubricants have been the object of much research aimed at further development to obtain stabler compounds capable of resisting more severe application conditions.
For this reason, the main application fields for these lubricants have been limited to such areas as the semiconductor industry using non-flammability, corrosive gases and low vapor pressure, the mechanical sector for bearings and machine conveyors and chains operated at high temperatures, and peripheral furnace equipment.
As the superior properties of fluorine-containing lubricants were recognized, however, their application range widened to include factory automation equipment, industrial robots, computer-related equipment, and electrical household appliances.
To permit its use for such equipment, a lubricant is required to meet a variety of specifications, and the fact is that the fluorine-containing lubricants available so far have, in most cases, not been able to fulfill these requirements.
The perfluoroalkyl polyether lubricants, that is, substances in which all hydrogen atoms of the alkyl group have been substituted by fluorine atoms, present difficulties in terms of their poor load resistance properties, if they have a low molecular weight.
By contrast, perfluoropolyethers having a high molecular weight have a low surface tension and favorable wetting properties but lack adhesion to metal surfaces to that, when used in machine parts rotating at a high speed, the lubricant will migrate and thus provide inadequate lubrication.
Further defects of these lubricants are due to their poor compatibility with other types of lubricants (mineral oil type lubricants) and their tendency to disperse under the action of applied centrifugal forces.
If, however, these lubricants are over-stabilized, the result will be that while their adsorption on metals remains poor, their lubricating effect as a lubricant for slide way movement will be very satisfactory in the initial period but this effect tends to diminish as the amount of lubricant appropriate for the lubrication of the equipment will decrease as time passes.
For this reason, some applications have necessitated a certain trade-off by sacrificing of the stability of the lubricant to a given extent for the sake of enhancing its adsorptivity.